A Comprehensive Insight on Adsorption of Polyaromatic Hydrocarbons, Chemical Oxygen Demand, Pharmaceuticals, and Chemical Dyes in Wastewaters Using Biowaste Carbonaceous Adsorbents

Table 1

Preparation techniques for AC and BC utilizing various materials.

	Pretreatment	Activation method	Pyrolysis method	Posttreatment	Physical properties				Ref.
					Surface area (m^2/g)	Pore vol. (cm^3/g)	Ash content	FTIR functional groups
Activated carbon (AC)
Oil palm shell	Washed, dried overnight at 105°C, cut into mesh size of 1–2 mm	Char soaked in KOH solution (1 : 1); Activated at 700°C (10°C/min) to a final temperature of 850°C; CO2 switched and activation held for 2 hr	Carbonized at 700°C for 2 hr at heating rate of 10°C/min under purified nitrogen flow of 150 cm^3/min	Cooled to room temperature under nitrogen flow; Washed with hot deionized water and 0.1 molar HCl until the pH of the washing solution reached 6–7	596.2	0.34		O–H stretching vibrations; C ≡ C stretching vibrations; C=C stretching vibration in aroma: C–OH stretching vibrations	[8]
Oil palm frond	Cut into small pieces (2 cm ×2 cm); Washed with water; Dried at 105°C; Crushed and sieved to mesh size of 1–4 mm	Char soaked in KOH solution (1 : 1, ) for 24 hr; Dehydrated in an oven overnight at 105°C	Carbonized at 700°C for 2 hr at heating rate of 10°C/min under purified nitrogen flow of 150 cm^3/min	Cooled to room temperature under nitrogen flow; Washed with hot DI water and 0.1 molar HCl until the pH was neutral					[42]
Palm tree leaves	Washed with deionized water, air-dried, and cut into small pieces	Soaking dried small pieces in 25% () H2SO4 at room temperature for 24 hr	Carbonization in oven at different temperatures for 24 hr	Cooled the AC to room temperature; Washed with deionized water; Dried at 105±1°C for 12 hr; Ground and sieved to particles between 300 μm and 425μm in size	64.12	0.0835		Hydroxyl (–OH); Bands of aliphatic C–H; Band of carboxyl group (C=O) in carboxylic acid; Bands of C=O (in -COO^−) or C=C centering; ν(O–H), ν(C–H), and ν(C=O) vibrations	[43]
Waste rice straw	Washed, air-dried, and cut into small pieces	Steam penetrated the reactor at a pace of 5 mL/min as the furnace hit 350°C and the heating proceeded for 1 hr until the final temperature was 550, 650, & 750°C	0.5 kg dried rice straw fed into fluidized bed reactor, at heating rate 50°C/10 min in the presence of N2 flow (300 mL/min)	Cooled down and washed with distilled water; Dried at 120°C and stored					[44]
Pecan shell	Washed, air-dried, and cut into small pieces	Steam activated at 900°C for 6 hr	Carbonized at 700°C	Cooled down and washed					[45]
		CO2 activated at 900°C for 6 hr
		H3PO4 activation at 170°C for 6 hr
Tea industry waste	Dried and ground to less than 150 μm size	20 g of tea wastes and 20 g of ZnCl2 mixed (1 : 1); A portion of 150 mL of distilled water added to the mixture and allowed to stand for 1 day; Solution was filtered	Carbonized in furnace starting at room temperature and increased to 700°C in 80 min under nitrogen at flow rate of 100 mL/min and maintained for 4 hr	Cooled to room temperature under nitrogen atmosphere; 2 times boiled in 2 M HCl and filtered; Dried at 105°C for 4 hr and kept in desiccator	1066	0.58	1.04		[46]
Rice husk	Washed, air-dried, and cut into small pieces	Impregnated 40g of rice husk with 100 mL of 40% () H3PO4	Heated up to 673 K in 2 hr and then held at this temperature for 3 hr	Cooled by washing until the pH became 6.5; The mass dried at 110°C	446				[47]
Tea waste	Washed with distilled water; Dried in oven at 60°C; Ground and sieved by mesh size of 60 μm	Carbon precursor was impregnated with 85% H3PO4 by varying the chemical ratio from 1 : 1 () to 1 : 3 and kept in oven at 60°C for 3 hr with occasional stirring	Carbonized at 400°C heating rate fixed on 5°C/min	Cooled down and washed initially with 0.1 M HCl and then with distilled water; Dried at 110°C for 24 hr and stored in desiccator	2054.4; (1 : 3)	1.747; (1 : 3)			[48]
Date stones	Washed with distilled water.; Dried in oven at 120°C.; Crushed and ground to particle size of 0.5-1 mm	The precursor was impregnated with KOH in a solid form (9 mmol : 1 g date stones) was activated at 800°C	The impregnated precursor was carbonized in a horizontal tubular furnace under nitrogen flow with a heating rate of 5°C/min for 1 h	The AC was immersed in HCl solution (0.1 M/L) for 3 hr; Filtered and washed with hot distilled water; Dried at 120°C and kept in tightly closed bottles	1209	0.550		Hydroxyl groups with hydrogen bending of adsorbed water; Aliphatic bond –CH, –CH2, and –CH3, aromatic C-C ring; –COO–, –CH3 group, C–O	[49]
		The precursor was impregnated with ZnCl2 in a solid form (1 : 1) and activated at 600°C.			1235	0.630
Tea waste	Boiled multiple times with distilled water; Washed and oven-dried at 103°C for 24 hr	Dried tea waste was modified by ZnCl2, K2CO3, KOH, and H2SO4 in 1 : 1 () overnight at room temperature; Filtered and dried in an oven at 103°C for 24 hr	Carbonized the activated material at 600°C for 2 hr	Washed and dried in an oven	865.4; 483.9; 416.4; 116.2	0.5032; 0.2222; 0.2155; 0.044		O-H & N-H stretching; C-H stretching of alkanes and alkenes, carbonyl group (C=O); C=C vibrations in aromatic rings; C-O stretching of alcohols	[50]
Wood sawdust	Ground and sieved to obtain a particle size of 0.5-1 mm	Before carbonization: chemically activated by KOH, and thermally activated under CO2 gas flow for 2 hr; After carbonization: impregnated the calcium solution of eggshell and AC (1 mL : 0.02 g) at required temperature	Carbonized in a horizontal furnace at 750°C under N2 atmosphere (150 mL/min)	Cooled and washed with boiled deionized water until neutral pH; Dried at 110°C for 24 hr; After impregnation: cleaned with hot distilled water and dried at 110°C for 24 hr	Before impreg.: 678.641; After impreg.: 433.486				[51]
Waste tires	Cleaning, washing, and drying	Treatment using 4.0 M/L HNO3 (1 : 20 g/mL) at 90°C for 3 h in a reflux condenser	7g AC-COCl was mixed with 100 mL of PEI solution. For 24 hr, the mixture was stirred at 150 rpm in a shaker at about 90°C.	Filtered, washed with distilled water, and dried at 110°C	363				[52]
Biochar (BC)
Tea waste	Washed and air dried; Crushed and ground to <1.0 mm size		Pyrolyzed at 300 and 700°C (7°C/min), with and without N2 purging (5 mL/min)	Washed and dried; Obtained: BC-300; BC-700; BC-300N; BC-700N	2.28; 342.22; 0.90; 421.31	0.0059; 0.0219; 0.0074; 0.0576	5.69; 10.87; 5.87; 11.60	O-H stretching band, aliphatic CAH stretching band, PO4^3-, and CO3^2-	[10]
		Steam activation: Samples were processed for an extra 45 min at maximum temperature with 5 mL/min of steam after the 2 hr pyrolysis cycle had passed.		Washed and dried.; Obtained: BC-300S; BC-700S	1.46; 576.09	0.0042; 0.1091	6.42; 16.73
Tea waste	Washed and dried in oven at 60°C for 48 h; Ground to <1 mm particle size		Pyrolyzed gradually at 700°C for 3 h with minimal oxygen at 7°C/min	Cooled down overnight in furnace	342.22	0.02	12.84		[15]
Rice husk	Washed and air-dried; Ground to <1 mm particle size				377	0.05	39.24
Banana peels	Washed and ground into 0.05 cm size	Soaked 4 g of raw material in 50 mL H3PO4 solutions for 2 hr at 0, 10, 20, 30, 40, & 50% concentration	The mixture was transferred to an autoclave and heated for 2 hr at 230°C	Dried overnight in oven at 80°C	45.27; 36.85; 31.65; 31.54; 30.91; 28.80			H-bonding hydroxyl groups, -CH2 or CH3 groups in carboxylic acid, C=O (C-O) stretching vibration of carboxyl groups	[16]
Rape straw	Cleaned and dried		Pyrolysis at 500°C in a high temperature furnace	Cleaned with water; Dried at 80°C for 24 hr in an oven	2.44		5.15	Vibration of free hydroxyl group, associative hydroxyl group, C=O of carboxylic acid, and C=C of aromatic ring	[17]
		10 g biochars mixed separately with 1 L solution of 25% HNO3 (), 25% H2O2 (m/m), and 5% KMnO4 (m/m); Then stirred for 4 hr at 40°C in a magnetic stirrer			2.39; 2.62; 90.2		1.68 3.52; 44.5
Miscanthus × giganteus	Washed and dried	H2O2 10%	Carbonized at 350 and 600°C.	Washed and dried	6.50 at 600°C	0.95			[35]
Dewatered sewage sludge	Dried at 105°C for 24 h and sieved into powder of 0.15-0.18 mm size		Pyrolyzed at 5°C/min till temp. reached 800°C and held for 2 h under N2 purging	Washed and dried in oven	49.45	0.07		Vibrations of the hydroxyl groups (-OH)	[39]
		Using a magnetic stirrer at 12 0 rpm at RT for 12 h, 12 g material powder and 12 g ultrafine dolomite powder were combined with 75 mL DI water; Put in a thermostat water-bath at 80°C and mixed for 2.5 h; Dried overnight in the oven at 105°C			11.31	0.03		Vibrations of the hydroxyl groups (-OH); Mg-O and O-Mg-O vibration bands
Peanut hull	Naturally dried; Peanut hull mixed with DI water (3 : 20, )	3 g of the carbonized sample placed into 20 mL 10% H2O2 solution for 2 hr at room temperature	Carbonize the mixture in autoclave held at 300°C for 5 hr at a pressure of about 1000 psi	Washed with DI water and dried at 80°C in an oven; Ground and sieved to a uniform size fraction of 0.5–1.0 mm	1.3	0.24; 0.25		Carbonyl groups	[53]
Colocasia esculenta	Cut into homogenous size, washed and dried for 2 days under sunlight; Later dried in hot air oven over night at 100°C	Passed superheated steam at rate of 1.5 kg/cm^2 at 700°C for 45 min; After 45 min of steam flow, the lag phase was sustained for 20 min at 700°C	Carbonized in a spherical shelled muffle furnace at 350-600°C for 45 min and maintained the temperature for 40 min	After carbonization, the temperature increased up to 700°C at 10°C/min. for activation; Activated sample was ground into particle size of 450 μm			3.67	Carboxylic acids, aldehydes and aromatic groups, terminal alkynes, alcohols and phenols	[54]
Lemon grass	Washed and dried	After carbonization sieved to 2 mm size; The final biochar added into 50 mL H2O2 solutions with different concentrations (—10%, 20%, 30%) for 3 hr at room temperature	Hydrothermal carbonization (10 g) was done with DI-water ( 1 : 1) at heating rate of 10°C/min. up to 200°C	Washed repeatedly; Oven dried at 60°C overnight; Ground into small sizes	27.2; 26.9; 27.3; 27.1	0.533; 0.537; 0.541; 0.548			[55]
Corn straws	Washed and dried	Dry corn straw (20 g) was impregnated with 35.6 mL 85% H3PO4 for 24 hr; Dried in the oven at 105°C for 7 hr	Oven dried material was pyrolyzed in a furnace to heat at 10°C/min to 300°C and held for 2 hr	Washed; Ground to 0.21 mm	1028.88	0.5378	4.01	OH groups, alkyl CH2 stretching, aromatic carboxyl groups, aromatic C=C and C=O, C=C in guaiacyl lignin, C=O of carboxylate ions, hydroxyl bending vibration, OH in phenolic	[56]
Tea waste	Washed and dried in oven at 105°C; Crushed to powder		Heated at 673 K for 1/2 h	Cooled down to room temperature; Grounded to a powder of 0.2 mm size	5.07	0.0079			[57]
		H2SO4 followed by NaNO3 were added to the dried biochar; KMnO4 was then added to the mixture with continuous stirring	Gradually heated from 323 K to 373 K and later 30% H2O2 added to the heated mixture and ultrasonicated for 15 min and filtered	Washed with distilled water for removal of excess acid; the resulting powder was dried in oven, grounded, sieved, and stored	11.833	0.0158		O-H bond stretching, C=C and C=O bonds stretching, C-O-C symmetric stretching
Spent P. ostreatus substrate	Air dried and screened (40-mesh sieve)		Carbonized in furnace for 2 hr at temp. 300°C, 500°C, and 700°C in oxygen-limited atm	Washed and dried	3.79; 18.05; 188.57	0.014; 0.061; 0.134	33.27; 52.35; 55.71	Aromatic C-H groups; C-O/C-O-C stretching vibrations of alcohols, phenols, and ether or ester groups, C=C ring stretching vibration	[58]
Spent shiitake substrate					12.97; 47.07; 218.70	0.028; 0.070; 0.138	28.02; 35.67; 42.28
Corn stalks	Dried in oven at 80°C (24 h); Crushed into powder	Crushed straw impregnated with 1.2 M K2CO3 solution (1 : 3, ); Dried at 80°C for 24 hr	Pyrolyzed in the furnace for 2 hr at 600°C	Ground and screened to <0.25mm size	680.36				[59]
Municipal sewage sludge and tea waste	Air-dried the sludge and tea waste, sieved, and meshed (100 size); Mixed both waste (1 : 1)		Pyrolyzed in muffle furnace at 300°C for 2 h	Cooled the biochar and sieved (100-mesh size)				OH groups; Aliphatic C-H group; C=O and C=C aromatic vibrations; C=O and C=H stretching vibrations	[60]
Pinewood biomass	Cut into small pieces and dried at 105°C in oven	Biochar soaked in H2O2 solution (1, 3, 10, 20, 30%, , 1 g : 20 mL).	Pyrolyzed at 400°C and held for 30min; Cooled down with N2 purging	Washed and dried at 105°C overnight				(C=C), carboxylic acid functionality, C-H stretching	[61]
Enteromorpha prolifera	Washed, air-dried, ground, and sieved (2 mm mesh)	Biochar soaked in HCl (1 M/L) and HF (40% w) mixture (180 : 20 mL) for 24 h	Pyrolyzed at 200–600°C with rate 10°C/min for 2 h under N2 purging (25mL/min)		205.32			Stretching of O–H in carboxyl and phenol functional groups, N–H symmetric stretching vibration, stretching of C=C and C=O	[62]
Miscanthus floridulus	Washed and dried in oven at 60°C; Crushed and sieved (0.15–0.25 mm)		Pyrolyzed for 6 h (5°C/min) at 450°C and kept for 1 h under N2 purging	Cooled and soaked in 1 M HCl for 12 h and washed				−OH groups, carbonyl/carboxyl (C=O), ether bond (C-O-C), C–O of phenolic group	[63]